xorg.conf

NAME

xorg.conf, xorg.conf.d - configuration files for
Xorg X server

INTRODUCTION

Xorg
supports several mechanisms for supplying/obtaining configuration and
run-time parameters: command line options, environment variables, the
xorg.conf and xorg.conf.d configuration files, auto-detection,
and fallback defaults. When the same information is supplied in more
than one way, the highest precedence mechanism is used. The list of
mechanisms is ordered from highest precedence to lowest. Note that not
all parameters can be supplied via all methods. The available command
line options and environment variables (and some defaults) are
described in the Xserver(1) and
Xorg(1) manual pages. Most configuration file
parameters, with their defaults, are described below. Driver and module
specific configuration parameters are described in the relevant driver
or module manual page.

DESCRIPTION

Xorg
uses a configuration file called
xorg.conf
and files ending in the suffix
.conf
from the directory
xorg.conf.d
for its initial setup.
The
xorg.conf
configuration file is searched for in the following places when the
server is started as a normal user:

where
<cmdline>
is a relative path (with no ".." components) specified with the
-config
command line option,
$XORGCONFIG
is the relative path (with no ".." components) specified by that
environment variable, and
<hostname>
is the machine's hostname as reported by
gethostname(3).

When the Xorg server is started by the "root" user, the config file
search locations are as follows:

where
<cmdline>
is the path specified with the
-config
command line option (which may be absolute or relative),
$XORGCONFIG
is the path specified by that
environment variable (absolute or relative),
$HOME
is the path specified by that environment variable (usually the home
directory), and
<hostname>
is the machine's hostname as reported by
gethostname(3).

Additional configuration files are searched for in the following
directories when the server is started as a normal user:

where
<cmdline>
is the path specified with the
-configdir
command line option (which may be absolute or relative).

Finally, configuration files will also be searched for in directories
reserved for system use. These are to separate configuration files from
the vendor or 3rd party packages from those of local administration.
These files are found in the following directories:

/usr/share/X11/xorg.conf.d/usr/share/X11/xorg.conf.d

The
xorg.conf
and
xorg.conf.d
files are composed of a number of sections which may be present in any order,
or omitted to use default configuration values.
Each section has the form:

The following obsolete section names are still recognised for compatibility
purposes.
In new config files, the
InputDevice
section should be used instead.

Keyboard Keyboard configuration
Pointer Pointer/mouse configuration

The old
XInput
section is no longer recognised.

The
ServerLayout
sections are at the highest level.
They bind together the input and output devices that will be used in a session.
The input devices are described in the
InputDevice
sections.
Output devices usually consist of multiple independent components (e.g.,
a graphics board and a monitor).
These multiple components are bound together in the
Screen
sections, and it is these that are referenced by the
ServerLayout
section.
Each
Screen
section binds together a graphics board and a monitor.
The graphics boards are described in the
Device
sections, and the monitors are described in the
Monitor
sections.

Config file keywords are case-insensitive, and "_" characters are
ignored.
Most strings (including
Option
names) are also case-insensitive, and insensitive to white space and
"_" characters.

Each config file entry usually takes up a single line in the file. They
consist of a keyword, which is possibly followed by one or more arguments,
with the number and types of the arguments depending on the keyword.
The argument types are:

Integer an integer number in decimal, hex or octal
Real a floating point number
String a string enclosed in double quote marks (")

Note: hex integer values must be prefixed with "0x", and octal values
with "0".

A special keyword called
Option
may be used to provide free-form data to various components of the server.
The
Option
keyword takes either one or two string arguments.
The first is the option name, and the optional second argument is the
option value.
Some commonly used option value types include:

Integer an integer number in decimal, hex or octal
Real a floating point number
String a sequence of characters
Boolean a boolean value (see below)
Frequency a frequency value (see below)

Note that
allOption
values, not just strings, must be enclosed in quotes.

Boolean options may optionally have a value specified.
When no value is specified, the option's value is
TRUE.
The following boolean option values are recognised as
TRUE:

1,
on,
true,
yes

and the following boolean option values are recognised as
FALSE:

0,
off,
false,
no

If an option name is prefixed with
"No",
then the option value is negated.

Frequency option values consist of a real number that is optionally
followed by one of the following frequency units:

Hz,
k,
kHz,
M,
MHz

When the unit name is omitted, the correct units will be determined from
the value and the expectations of the appropriate range of the value.
It is recommended that the units always be specified when using frequency
option values to avoid any errors in determining the value.

FILES SECTION

The
Files
section is used to specify some path names required by the server.
Some of these paths can also be set from the command line (see
Xserver(1)
and
Xorg(1)).
The command line settings override the values specified in the config
file.
The
Files
section is optional, as are all of the entries that may appear in it.

The entries that can appear in this section are:

FontPath "path"

sets the search path for fonts.
This path is a comma separated list of font path elements which the Xorg
server searches for font databases.
Multiple
FontPath
entries may be specified, and they will be concatenated to build up the
fontpath used by the server. Font path elements can be absolute
directory paths, catalogue directories or a font server identifier. The
formats of the later two are explained below:

Catalogue directories:

Catalogue directories can be specified using the prefix catalogue:
before the directory name. The directory can then be populated with
symlinks pointing to the real font directories, using the following
syntax in the symlink name:

<identifier>:[attribute]:pri=<priority>

where
<identifier>
is an alphanumeric identifier,
[attribute]
is an attribute which will be passed to the underlying FPE and
<priority>
is a number used to order the fontfile FPEs. Examples:

where
<trans>
is the transport type to use to connect to the font server (e.g.,
unix
for UNIX-domain sockets or
tcp
for a TCP/IP connection),
<hostname>
is the hostname of the machine running the font server, and
<port-number>
is the port number that the font server is listening on (usually 7100).

When this entry is not specified in the config file, the server falls back
to the compiled-in default font path, which contains the following
font path elements (which can be set inside a catalogue directory):

Font path elements that are found to be invalid are removed from the
font path when the server starts up.

ModulePath "path"

sets the search path for loadable Xorg server modules.
This path is a comma separated list of directories which the Xorg server
searches for loadable modules loading in the order specified.
Multiple
ModulePath
entries may be specified, and they will be concatenated to build the
module search path used by the server. The default module path is

/usr/lib/xorg/modules

XkbDir "path"

sets the base directory for keyboard layout files. The
-xkbdir
command line option can be used to override this. The default directory is

/usr/share/X11/xkb

SERVERFLAGS SECTION

In addition to options specific to this section (described below), the
ServerFlags
section is used to specify some global
Xorg server options.
All of the entries in this section are
Options,
although for compatibility purposes some of the old style entries are
still recognised.
Those old style entries are not documented here, and using them is
discouraged.
The
ServerFlags
section is optional, as are the entries that may be specified in it.

Options
specified in this section (with the exception of the
"DefaultServerLayout"Option)
may be overridden by
Options
specified in the active
ServerLayout
section.
Options with command line equivalents are overridden when their command
line equivalent is used.
The options recognised by this section are:

Option "DefaultServerLayout" "layout-id"

This specifies the default
ServerLayout
section to use in the absence of the
-layout
command line option.

Option "NoTrapSignals" "boolean"

This prevents the Xorg server from trapping a range of unexpected fatal
signals and exiting cleanly.
Instead, the Xorg server will die and drop core where the fault occurred.
The default behaviour is for the Xorg server to exit cleanly, but still drop a
core file.
In general you never want to use this option unless you are debugging an Xorg
server problem and know how to deal with the consequences.

Option "UseSIGIO" "boolean"

This controls whether the Xorg server requests that events from
input devices be reported via a SIGIO signal handler (also known as SIGPOLL
on some platforms), or only reported via the standard select(3) loop.
The default behaviour is platform specific. In general you do not want to
use this option unless you are debugging the Xorg server, or
working around a specific bug until it is fixed, and understand the
consequences.

Option "DontVTSwitch" "boolean"

This disallows the use of the
Ctrl+Alt+Fn
sequence (where
Fn
refers to one of the numbered function keys).
That sequence is normally used to switch to another "virtual terminal"
on operating systems that have this feature.
When this option is enabled, that key sequence has no special meaning and
is passed to clients.
Default: off.

Option "DontZap" "boolean"

This disallows the use of the
Terminate_Server
XKB action (usually on Ctrl+Alt+Backspace, depending on XKB options).
This action is normally used to terminate the Xorg server.
When this option is enabled, the action has no effect.
Default: off.

Option "DontZoom" "boolean"

This disallows the use of the
Ctrl+Alt+Keypad-Plus
and
Ctrl+Alt+Keypad-Minus
sequences.
These sequences allows you to switch between video modes.
When this option is enabled, those key sequences have no special meaning
and are passed to clients.
Default: off.

Option "DisableVidModeExtension" "boolean"

This disables the parts of the VidMode extension used by the xvidtune client
that can be used to change the video modes.
Default: the VidMode extension is enabled.

Option "AllowNonLocalXvidtune" "boolean"

This allows the xvidtune client (and other clients that use the VidMode
extension) to connect from another host.
Default: off.

Option "AllowMouseOpenFail" "boolean"

This tells the mousedrv(4) and vmmouse(4)
drivers to not report failure if the mouse device can't be opened/initialised.
It has no effect on the evdev(4) or other drivers.
Default: false.

Option "BlankTime" "time"

sets the inactivity timeout for the
blank
phase of the screensaver.
time
is in minutes.
This is equivalent to the Xorg server's
-s
flag, and the value can be changed at run-time with
xset(1).
Default: 10 minutes.

Option "StandbyTime" "time"

sets the inactivity timeout for the
standby
phase of DPMS mode.
time
is in minutes, and the value can be changed at run-time with
xset(1).
Default: 10 minutes.
This is only suitable for VESA DPMS compatible monitors, and may not be
supported by all video drivers.
It is only enabled for screens that have the
"DPMS"
option set (see the MONITOR section below).

Option "SuspendTime" "time"

sets the inactivity timeout for the
suspend
phase of DPMS mode.
time
is in minutes, and the value can be changed at run-time with
xset(1).
Default: 10 minutes.
This is only suitable for VESA DPMS compatible monitors, and may not be
supported by all video drivers.
It is only enabled for screens that have the
"DPMS"
option set (see the MONITOR section below).

Option "OffTime" "time"

sets the inactivity timeout for the
off
phase of DPMS mode.
time
is in minutes, and the value can be changed at run-time with
xset(1).
Default: 10 minutes.
This is only suitable for VESA DPMS compatible monitors, and may not be
supported by all video drivers.
It is only enabled for screens that have the
"DPMS"
option set (see the MONITOR section below).

Option "Pixmap" "bpp"

This sets the pixmap format to use for depth 24.
Allowed values for
bpp
are 24 and 32.
Default: 32 unless driver constraints don't allow this (which is rare).
Note: some clients don't behave well when this value is set to 24.

Option "NoPM" "boolean"

Disables something to do with power management events.
Default: PM enabled on platforms that support it.

Option "Xinerama" "boolean"

enable or disable XINERAMA extension.
Default is disabled.

Option "AIGLX" "boolean"

enable or disable AIGLX. AIGLX is enabled by default.

Option "DRI2" "boolean"

enable or disable DRI2. DRI2 is disabled by default.

Option "GlxVisuals" "string"

This option controls how many GLX visuals the GLX modules sets up.
The default value is
typical,
which will setup up a typical subset of
the GLXFBConfigs provided by the driver as GLX visuals. Other options are
minimal,
which will set up the minimal set allowed by the GLX specification and
all
which will setup GLX visuals for all GLXFBConfigs.

Option "UseDefaultFontPath" "boolean"

Include the default font path even if other paths are specified in
xorg.conf. If enabled, other font paths are included as well. Enabled by
default.

Option "IgnoreABI" "boolean"

Allow modules built for a different, potentially incompatible version of
the X server to load. Disabled by default.

Option "AutoAddDevices" "boolean"

If this option is disabled, then no devices will be added from the HAL or
udev backends. Enabled by default.

Option "AutoEnableDevices" "boolean"

If this option is disabled, then the devices will be added (and the
DevicePresenceNotify event sent), but not enabled, thus leaving policy up
to the client.
Enabled by default.

Option "AutoAddGPU" "boolean"

If this option is disabled, then no GPU devices will be added from the udev
backend. Enabled by default. (May need to be disabled to setup Xinerama).

Option "Log" "string"

This option controls whether the log is flushed and/or synced to disk after
each message.
Possible values are
flush
or
sync.
Unset by default.

MODULE SECTION

The
Module
section is used to specify which Xorg server modules should be loaded.
This section is ignored when the Xorg server is built in static form.
The type of modules normally loaded in this section are Xorg server
extension modules.
Most other module types are loaded automatically when they are needed via
other mechanisms.
The
Module
section is optional, as are all of the entries that may be specified in
it.

Entries in this section may be in two forms.
The first and most commonly used form is an entry that uses the
Load
keyword, as described here:

Load "modulename"

This instructs the server to load the module called
modulename.
The module name given should be the module's standard name, not the
module file name.
The standard name is case-sensitive, and does not include the "lib"
or "cyg" prefixes, or the ".so" or ".dll" suffixes.

Example: the DRI extension module can be loaded with the following entry:

Load "dri"

Disable "modulename"

This instructs the server to not load the module called
modulename.
Some modules are loaded by default in the server, and this overrides that
default. If a
Load
instruction is given for the same module, it overrides the
Disable
instruction and the module is loaded. The module name given should be the
module's standard name, not the module file name. As with the
Load
instruction, the standard name is case-sensitive, and does not include the
"lib" prefix, or the ".a", ".o", or ".so" suffixes.

The second form of entry is a
SubSection,
with the subsection name being the module name, and the contents of the
SubSection
being
Options
that are passed to the module when it is loaded.

Example: the extmod module (which contains a miscellaneous group of
server extensions) can be loaded, with the XFree86-DGA extension
disabled by using the following entry:

SubSection "extmod" Option "omit XFree86-DGA"EndSubSection

Modules are searched for in each directory specified in the
ModulePath
search path, and in the drivers, extensions, input, internal, and
multimedia subdirectories of each of those directories.
In addition to this, operating system specific subdirectories of all
the above are searched first if they exist.

To see what extension modules are available, check the extensions
subdirectory under:

/usr/lib/xorg/modules

The "extmod", "dbe", "dri", "dri2", "glx",
and "record" extension modules are loaded automatically, if they
are present, unless disabled with "Disable" entries.
It is recommended
that at very least the "extmod" extension module be loaded.
If it isn't, some commonly used server extensions (like the SHAPE
extension) will not be available.

EXTENSIONS SECTION

The
Extensions
section is used to specify which X11 protocol extensions should be enabled
or disabled.
The
Extensions
section is optional, as are all of the entries that may be specified in
it.

Entries in this section are listed as Option statements with the name of
the extension as the first argument, and a boolean value as the second.
The extension name is case-sensitive, and matches the form shown in the output
of "Xorg -extension ?".

Example: the MIT-SHM extension can be disabled with the following entry:

Section "Extensions" Option "MIT-SHM" "Disable"EndSection

INPUTDEVICE SECTION

The config file may have multiple
InputDevice
sections.
Recent X servers employ HAL or udev backends for input device enumeration
and input hotplugging. It is usually not
necessary to provide
InputDevice
sections in the xorg.conf if hotplugging is in use (i.e. AutoAddDevices is
enabled). If hotplugging is enabled,
InputDevice
sections using the
mouse, kbd
and
vmmouse
driver will be ignored.

If hotplugging is disabled, there will normally
be at least two: one for the core (primary) keyboard
and one for the core pointer.
If either of these two is missing, a default configuration for the missing
ones will be used. In the absence of an explicitly specified core input
device, the first
InputDevice
marked as
CorePointer
(or
CoreKeyboard)
is used.
If there is no match there, the first
InputDevice
that uses the "mouse" (or "kbd") driver is used.
The final fallback is to use built-in default configurations.
Currently the default configuration may not work as expected on all platforms.

The
Identifier
and
Driver
entries are required in all
InputDevice
sections.
All other entries are optional.

The
Identifier
entry specifies the unique name for this input device.
The
Driver
entry specifies the name of the driver to use for this input device.
When using the loadable server, the input driver module
"inputdriver"
will be loaded for each active
InputDevice
section.
An
InputDevice
section is considered active if it is referenced by an active
ServerLayout
section, if it is referenced by the
-keyboard
or
-pointer
command line options, or if it is selected implicitly as the core pointer
or keyboard device in the absence of such explicit references.
The most commonly used input drivers are
evdev(4)
on Linux systems, and
kbd(4)
and
mousedrv(4)
on other platforms.

InputDevice
sections recognise some driver-independent
Options,
which are described here.
See the individual input driver manual pages for a description of the
device-specific options.

Option "AutoServerLayout" "boolean"

Always add the device to the ServerLayout section used by this instance of
the server. This affects implied layouts as well as explicit layouts
specified in the configuration and/or on the command line.

Option "CorePointer"

Deprecated, see
Floating

Option "CoreKeyboard"

Deprecated, see
Floating

Option "AlwaysCore" "boolean"

Deprecated, see
Floating

Option "SendCoreEvents" "boolean"

Deprecated, see
Floating

Option "Floating" "boolean"

When enabled, the input device is set up floating and does not
report events through any master device or control a cursor. The device is
only available to clients using the X Input Extension API. This option is
disabled by default.
The options
CorePointer,CoreKeyboard,AlwaysCore,
and
SendCoreEvents,
are the inverse of option
Floating
(i.e.
SendCoreEvents "on"
is equivalent to
Floating "off"
).

This option controls the startup behavior only, a device
may be reattached or set floating at runtime.

Option "TransformationMatrix" "abcdefghi"

Specifies the 3x3 transformation matrix for absolute input devices. The
input device will be bound to the area given in the matrix. In most
configurations, "a" and "e" specify the width and height of the area the
device is bound to, and "c" and "f" specify the x and y offset of the area.
The value range is 0 to 1, where 1 represents the width or height of all
root windows together, 0.5 represents half the area, etc. The values
represent a 3x3 matrix, with the first, second and third group of three
values representing the first, second and third row of the matrix,
respectively. The identity matrix is "1 0 0 0 1 0 0 0 1".

POINTER ACCELERATION

For pointing devices, the following options control how the pointer
is accelerated or decelerated with respect to physical device motion. Most of
these can be adjusted at runtime, see the xinput(1) man page for details. Only
the most important acceleration options are discussed here.

Option "AccelerationProfile" "integer"

Select the profile. In layman's terms, the profile constitutes the "feeling" of
the acceleration. More formally, it defines how the transfer function (actual
acceleration as a function of current device velocity and acceleration controls)
is constructed. This is mainly a matter of personal preference.

Makes the pointer go
deceleration
times slower than normal. Most useful for high-resolution devices. A value
between 0 and 1 will speed up the pointer.

Option "AdaptiveDeceleration" "real"

Allows to actually decelerate the pointer when going slow. At most, it will be
adaptive deceleration
times slower. Enables precise pointer placement without sacrificing speed.

Option "AccelerationScheme" "string"

Selects the scheme, which is the underlying algorithm.

predictable default algorithm (behaving more predictable)lightweight old acceleration code (as specified in the X protocol spec)none no acceleration or deceleration

Option "AccelerationNumerator" "integer"

Option "AccelerationDenominator" "integer"

Set numerator and denominator of the acceleration factor. The acceleration
factor is a rational which, together with threshold, can be used to tweak
profiles to suit the users needs. The
simple
and
limited
profiles use it directly (i.e. they accelerate by the factor), for other
profiles it should hold that a higher acceleration factor leads to a faster
pointer. Typically, 1 is unaccelerated and values up to 5 are sensible.

Option "AccelerationThreshold" "integer"

Set the threshold, which is roughly the velocity (usually device units per 10
ms) required for acceleration to become effective. The precise effect varies
with the profile however.

INPUTCLASS SECTION

The config file may have multiple
InputClass
sections.
These sections are optional and are used to provide configuration for a
class of input devices as they are automatically added. An input device can
match more than one
InputClass
section. Each class can override settings from a previous class, so it is
best to arrange the sections with the most generic matches first.

The
Identifier
entry is required in all
InputClass
sections.
All other entries are optional.

The
Identifier
entry specifies the unique name for this input class.
The
Driver
entry specifies the name of the driver to use for this input device.
After all classes have been examined, the
"inputdriver"
module from the first
Driver
entry will be enabled when using the loadable server.

When an input device is automatically added, its characteristics are
checked against all
InputClass
sections. Each section can contain optional entries to narrow the match
of the class. If none of the optional entries appear, the
InputClass
section is generic and will match any input device. If more than one of
these entries appear, they all must match for the configuration to apply.

There are two types of match entries used in
InputClass
sections. The first allows various tokens to be matched against attributes
of the device. An entry can be constructed to match attributes from different
devices by separating arguments with a '|' character. Multiple entries of the
same type may be supplied to add multiple matching conditions on the same
attribute. For example:

This entry can be used to check if the substring
"matchproduct"
occurs in the device's product name.

MatchVendor "matchvendor"

This entry can be used to check if the substring
"matchvendor"
occurs in the device's vendor name.

MatchDevicePath "matchdevice"

This entry can be used to check if the device file matches the
"matchdevice"
pathname pattern.

MatchOS "matchos"

This entry can be used to check if the operating system matches the
case-insensitive
"matchos"
string. This entry is only supported on platforms providing the
uname(2)
system call.

MatchPnPID "matchpnp"

The device's Plug and Play (PnP) ID can be checked against the
"matchpnp"
shell wildcard pattern.

MatchUSBID "matchusb"

The device's USB ID can be checked against the
"matchusb"
shell wildcard pattern. The ID is constructed as lowercase hexadecimal numbers
separated by a ':'. This is the same format as the
lsusb(8)
program.

MatchDriver "matchdriver"

Check the case-sensitive string
"matchdriver"
against the currently configured driver of the device. Ordering of sections
using this entry is important since it will not match unless the driver has
been set by the config backend or a previous
InputClass
section.

MatchTag "matchtag"

This entry can be used to check if tags assigned by the config backend
matches the
"matchtag"
pattern. A match is found if at least one of the tags given in
"matchtag"
matches at least one of the tags assigned by the backend.

MatchLayout "matchlayout"

Check the case-sensitive string
"matchlayout"
against the currently active
ServerLayout
section. The empty string "" matches an implicit layout which appears
if no named
ServerLayout
sections have been found.

The second type of entry is used to match device types. These entries take a
boolean argument similar to
Option
entries.

MatchIsKeyboard "bool"

MatchIsPointer "bool"

MatchIsJoystick "bool"

MatchIsTablet "bool"

MatchIsTouchpad "bool"

MatchIsTouchscreen "bool"

When an input device has been matched to the
InputClass
section, any
Option
entries are applied to the device. One
InputClass
specific
Option
is recognized. See the
InputDevice
section above for a description of the remaining
Option
entries.

Option "Ignore" "boolean"

This optional entry specifies that the device should be ignored entirely,
and not added to the server. This can be useful when the device is handled
by another program and no X events should be generated.

OUTPUTCLASS SECTION

The config file may have multiple
OutputClass
sections.
These sections are optional and are used to provide configuration for a
class of output devices as they are automatically added.
An output device can match more than one
OutputClass
section.
Each class can override settings from a previous class, so it is best to
arrange the sections with the most generic matches first.

OutputClass
sections have the following format:

Section "OutputClass" Identifier "name" entries ...EndSection

The
Identifier
entry is required in all
OutputClass
sections.
All other entries are optional.

The
Identifier
entry specifies the unique name for this output class.
The
Driver
entry specifies the name of the driver to use for this output device.
After all classes have been examined, the
"outputdriver"
module from the first
Driver
entry will be enabled when using the loadable server.

When an output device is automatically added, its characteristics are
checked against all
OutputClass
sections.
Each section can contain optional entries to narrow the match of the class.
If none of the optional entries appear, the
OutputClass
section is generic and will match any output device.
If more than one of these entries appear, they all must match for the
configuration to apply.

The following list of tokens can be matched against attributes of the device.
An entry can be constructed to match attributes from different devices by
separating arguments with a '|' character.

The
Identifier
and
Driver
entries are required in all
Device
sections. All other entries are optional.

The
Identifier
entry specifies the unique name for this graphics device.
The
Driver
entry specifies the name of the driver to use for this graphics device.
When using the loadable server, the driver module
"driver"
will be loaded for each active
Device
section.
A
Device
section is considered active if it is referenced by an active
Screen
section.

Device
sections recognise some driver-independent entries and
Options,
which are described here.
Not all drivers make use of these
driver-independent entries, and many of those that do don't require them
to be specified because the information is auto-detected.
See the individual graphics driver manual pages for further information
about this, and for a description of the device-specific options.
Note that most of the
Options
listed here (but not the other entries) may be specified in the
Screen
section instead of here in the
Device
section.

BusID "bus-id"

This specifies the bus location of the graphics card.
For PCI/AGP cards,
the
bus-id
string has the form
PCI:bus:device:function
(e.g., "PCI:1:0:0" might be appropriate for an AGP card).
This field is usually optional in single-head configurations when using
the primary graphics card.
In multi-head configurations, or when using a secondary graphics card in a
single-head configuration, this entry is mandatory.
Its main purpose is to make an unambiguous connection between the device
section and the hardware it is representing.
This information can usually be found by running the pciaccess tool
scanpci.

Screen number

This option is mandatory for cards where a single PCI entity can drive more
than one display (i.e., multiple CRTCs sharing a single graphics accelerator
and video memory).
One
Device
section is required for each head, and this
parameter determines which head each of the
Device
sections applies to.
The legal values of
number
range from 0 to one less than the total number of heads per entity.
Most drivers require that the primary screen (0) be present.

Chipset "chipset"

This usually optional entry specifies the chipset used on the graphics
board.
In most cases this entry is not required because the drivers will probe the
hardware to determine the chipset type.
Don't specify it unless the driver-specific documentation recommends that you
do.

Ramdac "ramdac-type"

This optional entry specifies the type of RAMDAC used on the graphics
board.
This is only used by a few of the drivers, and in most cases it is not
required because the drivers will probe the hardware to determine the
RAMDAC type where possible.
Don't specify it unless the driver-specific documentation recommends that you
do.

DacSpeed speed

DacSpeed speed-8 speed-16 speed-24 speed-32

This optional entry specifies the RAMDAC speed rating (which is usually
printed on the RAMDAC chip).
The speed is in MHz.
When one value is given, it applies to all framebuffer pixel sizes.
When multiple values are given, they apply to the framebuffer pixel sizes
8, 16, 24 and 32 respectively.
This is not used by many drivers, and only needs to be specified when the
speed rating of the RAMDAC is different from the defaults built in to
driver, or when the driver can't auto-detect the correct defaults.
Don't specify it unless the driver-specific documentation recommends that you
do.

Clocks clock ...

specifies the pixel that are on your graphics board.
The clocks are in MHz, and may be specified as a floating point number.
The value is stored internally to the nearest kHz.
The ordering of the clocks is important.
It must match the order in which they are selected on the graphics board.
Multiple
Clocks
lines may be specified, and each is concatenated to form the list.
Most drivers do not use this entry, and it is only required for some older
boards with non-programmable clocks.
Don't specify this entry unless the driver-specific documentation explicitly
recommends that you do.

ClockChip "clockchip-type"

This optional entry is used to specify the clock chip type on graphics
boards which have a programmable clock generator.
Only a few Xorg drivers support programmable clock chips.
For details, see the appropriate driver manual page.

VideoRam mem

This optional entry specifies the amount of video ram that is installed
on the graphics board.
This is measured in kBytes.
In most cases this is not required because the Xorg server probes
the graphics board to determine this quantity.
The driver-specific documentation should indicate when it might be needed.

BiosBase baseaddress

This optional entry specifies the base address of the video BIOS for
the VGA board.
This address is normally auto-detected, and should only be specified if the
driver-specific documentation recommends it.

MemBase baseaddress

This optional entry specifies the memory base address of a graphics
board's linear frame buffer.
This entry is not used by many drivers, and it should only be specified if
the driver-specific documentation recommends it.

IOBase baseaddress

This optional entry specifies the IO base address.
This entry is not used by many drivers, and it should only be specified if
the driver-specific documentation recommends it.

ChipID id

This optional entry specifies a numerical ID representing the chip type.
For PCI cards, it is usually the device ID.
This can be used to override the auto-detection, but that should only be done
when the driver-specific documentation recommends it.

ChipRev rev

This optional entry specifies the chip revision number.
This can be used to override the auto-detection, but that should only be done
when the driver-specific documentation recommends it.

TextClockFreq freq

This optional entry specifies the pixel clock frequency that is used
for the regular text mode.
The frequency is specified in MHz.
This is rarely used.

MatchSeat seat-id

Only apply this
Device
section if X server was started with
-seatseat-id
option.

Option "ModeDebug" "boolean"

Enable printing of additional debugging information about modesetting to
the server log.

Options

Option flags may be specified in the
Device
sections.
These include driver-specific options and driver-independent options.
The former are described in the driver-specific documentation.
Some of the latter are described below in the section about the
Screen
section, and they may also be included here.

VIDEOADAPTOR SECTION

Nobody wants to say how this works.
Maybe nobody knows ...

MONITOR SECTION

The config file may have multiple
Monitor
sections.
There should normally be at least one, for the monitor being used,
but a default configuration will be created when one isn't specified.

Monitor
sections have the following format:

Section "Monitor" Identifier "name" entries ...EndSection

The only mandatory entry in a
Monitor
section is the
Identifier
entry.

The
Identifier
entry specifies the unique name for this monitor.
The
Monitor
section may be used to provide information about the specifications of the
monitor, monitor-specific
Options,
and information about the video modes to use with the monitor.

With RandR 1.2-enabled drivers, monitor sections may be tied to specific
outputs of the video card. Using the name of the output defined by the video
driver plus the identifier of a monitor section, one associates a monitor
section with an output by adding an option to the Device section in the
following format:

Option "Monitor-outputname" "monitorsection"

(for example,
Option "Monitor-VGA" "VGA monitor"
for a VGA output)

In the absence of specific association of monitor sections to outputs, if a
monitor section is present the server will associate it with an output to
preserve compatibility for previous single-head configurations.

Specifying video modes is optional because the server will use the DDC or other
information provided by the monitor to automatically configure the list of
modes available.
When modes are specified explicitly in the
Monitor
section (with the
Mode,
ModeLine,
or
UseModes
keywords), built-in modes with the same names are not included.
Built-in modes with different names are, however, still implicitly included,
when they meet the requirements of the monitor.

The entries that may be used in
Monitor
sections are described below.

VendorName "vendor"

This optional entry specifies the monitor's manufacturer.

ModelName "model"

This optional entry specifies the monitor's model.

HorizSync horizsync-range

gives the range(s) of horizontal sync frequencies supported by the
monitor.
horizsync-range
may be a comma separated list of either discrete values or ranges of
values.
A range of values is two values separated by a dash.
By default the values are in units of kHz.
They may be specified in MHz or Hz
if
MHz
or
Hz
is added to the end of the line.
The data given here is used by the Xorg server to determine if video
modes are within the specifications of the monitor.
This information should be available in the monitor's handbook.
If this entry is omitted, a default range of 28-33kHz is used.

VertRefresh vertrefresh-range

gives the range(s) of vertical refresh frequencies supported by the
monitor.
vertrefresh-range
may be a comma separated list of either discrete values or ranges of
values.
A range of values is two values separated by a dash.
By default the values are in units of Hz.
They may be specified in MHz or kHz
if
MHz
or
kHz
is added to the end of the line.
The data given here is used by the Xorg server to determine if video
modes are within the specifications of the monitor.
This information should be available in the monitor's handbook.
If this entry is omitted, a default range of 43-72Hz is used.

DisplaySize width height

This optional entry gives the width and height, in millimetres, of the
picture area of the monitor.
If given this is used to calculate the horizontal and vertical pitch (DPI) of
the screen.

Gamma gamma-value

Gamma red-gamma green-gamma blue-gamma

This is an optional entry that can be used to specify the gamma correction
for the monitor.
It may be specified as either a single value or as three separate RGB values.
The values should be in the range 0.1 to 10.0, and the default is 1.0.
Not all drivers are capable of using this information.

UseModes "modesection-id"

Include the set of modes listed in the
Modes
section called
modesection-id.
This makes all of the modes defined in that section available for use by
this monitor.

Mode "name"

This is an optional multi-line entry that can be used to provide
definitions for video modes for the monitor.
In most cases this isn't necessary because the built-in set of VESA standard
modes will be sufficient.
The
Mode
keyword indicates the start of a multi-line video mode description.
The mode description is terminated with the
EndMode
keyword.
The mode description consists of the following entries:

DotClock clock

is the dot (pixel) clock rate to be used for the mode.

HTimings hdisp hsyncstart hsyncend htotal

specifies the horizontal timings for the mode.

VTimings vdisp vsyncstart vsyncend vtotal

specifies the vertical timings for the mode.

Flags "flag" ...

specifies an optional set of mode flags, each of which is a separate
string in double quotes.
"Interlace"
indicates that the mode is interlaced.
"DoubleScan"
indicates a mode where each scanline is doubled.
"+HSync"
and
"-HSync"
can be used to select the polarity of the HSync signal.
"+VSync"
and
"-VSync"
can be used to select the polarity of the VSync signal.
"Composite"
can be used to specify composite sync on hardware where this is supported.
Additionally, on some hardware,
"+CSync"
and
"-CSync"
may be used to select the composite sync polarity.

HSkew hskew

specifies the number of pixels (towards the right edge of the screen) by
which the display enable signal is to be skewed.
Not all drivers use this information.
This option might become necessary to override the default value supplied
by the server (if any).
"Roving" horizontal lines indicate this value needs to be increased.
If the last few pixels on a scan line appear on the left of the screen,
this value should be decreased.

VScan vscan

specifies the number of times each scanline is painted on the screen.
Not all drivers use this information.
Values less than 1 are treated as 1, which is the default.
Generally, the
"DoubleScan"Flag
mentioned above doubles this value.

ModeLine "name" mode-description

This entry is a more compact version of the
Mode
entry, and it also can be used to specify video modes for the monitor.
This is a single line format for specifying video modes.
In most cases this isn't necessary because the built-in set of VESA
standard modes will be sufficient.

The
mode-description
is in four sections, the first three of which are mandatory.
The first is the dot (pixel) clock.
This is a single number specifying the pixel clock rate for the mode in
MHz.
The second section is a list of four numbers specifying the horizontal
timings.
These numbers are the
hdisp,
hsyncstart,
hsyncend,
and
htotal
values.
The third section is a list of four numbers specifying the vertical
timings.
These numbers are the
vdisp,
vsyncstart,
vsyncend,
and
vtotal
values.
The final section is a list of flags specifying other characteristics of
the mode.
Interlace
indicates that the mode is interlaced.
DoubleScan
indicates a mode where each scanline is doubled.
+HSync
and
-HSync
can be used to select the polarity of the HSync signal.
+VSync
and
-VSync
can be used to select the polarity of the VSync signal.
Composite
can be used to specify composite sync on hardware where this is supported.
Additionally, on some hardware,
+CSync
and
-CSync
may be used to select the composite sync polarity.
The
HSkew
and
VScan
options mentioned above in the
Mode
entry description can also be used here.

Option "DPMS" "bool"

This option controls whether the server should enable the DPMS extension
for power management for this screen. The default is to enable the
extension.

Option "SyncOnGreen" "bool"

This option controls whether the video card should drive the sync signal
on the green color pin. Not all cards support this option, and most
monitors do not require it. The default is off.

Option "Primary" "bool"

This optional entry specifies that the monitor should be treated as the primary
monitor. (RandR 1.2-supporting drivers only)

Option "PreferredMode" "name"

This optional entry specifies a mode to be marked as the preferred initial mode
of the monitor.
(RandR 1.2-supporting drivers only)

Option "ZoomModes" "namename..."

This optional entry specifies modes to be marked as zoom modes.
It is possible to switch to the next and previous mode via
Ctrl+Alt+Keypad-Plus and Ctrl+Alt+Keypad-Minus.
All these keypad available modes are selected from the screen mode list.
This list is a copy of the compatibility output monitor mode list.
Since this output is the output connected to the lowest
dot-area monitor, as determined from its largest size mode, that
monitor defines the available zoom modes.
(RandR 1.2-supporting drivers only)

Option "Position" "xy"

This optional entry specifies the position of the monitor within the X
screen.
(RandR 1.2-supporting drivers only)

Option "LeftOf" "output"

This optional entry specifies that the monitor should be positioned to the
left of the output (not monitor) of the given name.
(RandR 1.2-supporting drivers only)

Option "RightOf" "output"

This optional entry specifies that the monitor should be positioned to the
right of the output (not monitor) of the given name.
(RandR 1.2-supporting drivers only)

Option "Above" "output"

This optional entry specifies that the monitor should be positioned above the
output (not monitor) of the given name.
(RandR 1.2-supporting drivers only)

Option "Below" "output"

This optional entry specifies that the monitor should be positioned below the
output (not monitor) of the given name.
(RandR 1.2-supporting drivers only)

Option "Enable" "bool"

This optional entry specifies whether the monitor should be turned on
at startup. By default, the server will attempt to enable all connected
monitors.
(RandR 1.2-supporting drivers only)

Option "DefaultModes" "bool"

This optional entry specifies whether the server should add supported default
modes to the list of modes offered on this monitor. By default, the server
will add default modes; you should only disable this if you can guarantee
that EDID will be available at all times, or if you have added custom modelines
which the server can use.
(RandR 1.2-supporting drivers only)

Option "MinClock" "frequency"

This optional entry specifies the minimum dot clock, in kHz, that is supported
by the monitor.

Option "MaxClock" "frequency"

This optional entry specifies the maximum dot clock, in kHz, that is supported
by the monitor.

Option "Ignore" "bool"

This optional entry specifies that the monitor should be ignored entirely,
and not reported through RandR. This is useful if the hardware reports the
presence of outputs that don't exist.
(RandR 1.2-supporting drivers only)

Option "Rotate" "rotation"

This optional entry specifies the initial rotation of the given monitor.
Valid values for rotation are "normal", "left", "right", and
"inverted".
(RandR 1.2-supporting drivers only)

MODES SECTION

The config file may have multiple
Modes
sections, or none.
These sections provide a way of defining sets of video modes independently
of the
Monitor
sections.
Monitor
sections may include the definitions provided in these sections by
using the
UseModes
keyword.
In most cases the
Modes
sections are not necessary because the built-in set of VESA standard modes
will be sufficient.

Modes
sections have the following format:

Section "Modes" Identifier "name" entries ...EndSection

The
Identifier
entry specifies the unique name for this set of mode descriptions.
The other entries permitted in
Modes
sections are the
Mode
and
ModeLine
entries that are described above in the
Monitor
section.

SCREEN SECTION

The config file may have multiple
Screen
sections.
There must be at least one, for the "screen" being used.
A "screen" represents the binding of a graphics device
(Device
section) and a monitor
(Monitor
section).
A
Screen
section is considered "active" if it is referenced by an active
ServerLayout
section or by the
-screen
command line option.
If neither of those is present, the first
Screen
section found in the config file is considered the active one.

The
Identifier
entry specifies the unique name for this screen.
The
Screen
section provides information specific to the whole screen, including
screen-specific
Options.
In multi-head configurations, there will be multiple active
Screen
sections, one for each head.
The entries available
for this section are:

Device "device-id"

This entry specifies the
Device
section to be used for this screen. When multiple graphics cards are
present, this is what ties a specific card to a screen. The
device-id
must match the
Identifier
of a
Device
section in the config file.

Monitor "monitor-id"

specifies which monitor description is to be used for this screen.
If a
Monitor
name is not specified, a default configuration is used.
Currently the default configuration may not function as expected on all
platforms.

VideoAdaptor "xv-id"

specifies an optional Xv video adaptor description to be used with this
screen.

DefaultDepth depth

specifies which color depth the server should use by default.
The
-depth
command line option can be used to override this.
If neither is specified, the default depth is driver-specific, but in most
cases is 8.

DefaultFbBpp bpp

specifies which framebuffer layout to use by default.
The
-fbbpp
command line option can be used to override this.
In most cases the driver will chose the best default value for this.
The only case where there is even a choice in this value is for depth 24,
where some hardware supports both a packed 24 bit framebuffer layout and a
sparse 32 bit framebuffer layout.

MatchSeat seat-id

Only apply this
Screen
section if X server was started with
-seatseat-id
option.

Options

Various
Option
flags may be specified in the
Screen
section.
Some are driver-specific and are described in the driver documentation.
Others are driver-independent, and will eventually be described here.

Option "Accel"

Enables 2D hardware acceleration.
This option is on by default, but it may be necessary to turn it off if
there are bugs in the driver.
There are many options to disable specific accelerated operations, listed
below.
Note that disabling an operation will have no effect if the operation is
not accelerated (whether due to lack of support in the hardware or in the
driver).

Option "InitPrimary" "boolean"

Use the Int10 module to initialize the primary graphics card.
Normally, only secondary cards are soft-booted using the Int10 module, as the
primary card has already been initialized by the BIOS at boot time.
Default: false.

Option "NoInt10" "boolean"

Disables the Int10 module, a module that uses the int10 call to the BIOS
of the graphics card to initialize it.
Default: false.

Option "NoMTRR"

Disables MTRR (Memory Type Range Register) support, a feature of modern
processors which can improve video performance by a factor of up to 2.5.
Some hardware has buggy MTRR support, and some video drivers have been
known to exhibit problems when MTRR's are used.

Each
Screen
section may optionally contain one or more
Display
subsections.
Those subsections provide depth/fbbpp specific configuration information,
and the one chosen depends on the depth and/or fbbpp that is being used for
the screen.
The
Display
subsection format is described in the section below.

DISPLAY SUBSECTION

Each
Screen
section may have multiple
Display
subsections.
The "active"
Display
subsection is the first that matches the depth and/or fbbpp values being
used, or failing that, the first that has neither a depth or fbbpp value
specified.
The
Display
subsections are optional.
When there isn't one that matches the depth and/or fbbpp values being used,
all the parameters that can be specified here fall back to their defaults.

Display
subsections have the following format:

SubSection "Display" Depth depth entries ... EndSubSection

Depth depth

This entry specifies what colour depth the
Display
subsection is to be used for.
This entry is usually specified, but it may be omitted to create a match-all
Display
subsection or when wishing to match only against the
FbBpp
parameter.
The range of
depth
values that are allowed depends on the driver.
Most drivers support 8, 15, 16 and 24.
Some also support 1 and/or 4, and some may support other values (like 30).
Note:
depth
means the number of bits in a pixel that are actually used to determine
the pixel colour.
32 is not a valid
depth
value.
Most hardware that uses 32 bits per pixel only uses 24 of them to hold the
colour information, which means that the colour depth is 24, not 32.

FbBpp bpp

This entry specifies the framebuffer format this
Display
subsection is to be used for.
This entry is only needed when providing depth 24 configurations that allow
a choice between a 24 bpp packed framebuffer format and a 32bpp sparse
framebuffer format.
In most cases this entry should not be used.

Weight red-weight green-weight blue-weight

This optional entry specifies the relative RGB weighting to be used
for a screen is being used at depth 16 for drivers that allow multiple
formats.
This may also be specified from the command line with the
-weight
option (see
Xorg(1)).

Virtual xdim ydim

This optional entry specifies the virtual screen resolution to be used.
xdim
must be a multiple of either 8 or 16 for most drivers, and a multiple
of 32 when running in monochrome mode.
The given value will be rounded down if this is not the case.
Video modes which are too large for the specified virtual size will be
rejected.
If this entry is not present, the virtual screen resolution will be set to
accommodate all the valid video modes given in the
Modes
entry.
Some drivers/hardware combinations do not support virtual screens.
Refer to the appropriate driver-specific documentation for details.

ViewPort x0 y0

This optional entry sets the upper left corner of the initial display.
This is only relevant when the virtual screen resolution is different
from the resolution of the initial video mode.
If this entry is not given, then the initial display will be centered in
the virtual display area.

Modes "mode-name" ...

This optional entry specifies the list of video modes to use.
Each
mode-name
specified must be in double quotes.
They must correspond to those specified or referenced in the appropriate
Monitor
section (including implicitly referenced built-in VESA standard modes).
The server will delete modes from this list which don't satisfy various
requirements.
The first valid mode in this list will be the default display mode for
startup.
The list of valid modes is converted internally into a circular list.
It is possible to switch to the next mode with
Ctrl+Alt+Keypad-Plus
and to the previous mode with
Ctrl+Alt+Keypad-Minus.
When this entry is omitted, the valid modes referenced by the appropriate
Monitor
section will be used. If the
Monitor
section contains no modes, then the selection will be taken from the
built-in VESA standard modes.

Visual "visual-name"

This optional entry sets the default root visual type.
This may also be specified from the command line (see the
Xserver(1)
man page).
The visual types available for depth 8 are (default is
PseudoColor):

StaticGrayGrayScaleStaticColorPseudoColorTrueColorDirectColor

The visual type available for the depths 15, 16 and 24 are (default is
TrueColor):

TrueColorDirectColor

Not all drivers support
DirectColor
at these depths.

The visual types available for the depth 4 are (default is
StaticColor):

StaticGrayGrayScaleStaticColorPseudoColor

The visual type available for the depth 1 (monochrome) is
StaticGray.

Black red green blue

This optional entry allows the "black" colour to be specified.
This is only supported at depth 1.
The default is black.

White red green blue

This optional entry allows the "white" colour to be specified.
This is only supported at depth 1.
The default is white.

Options

Option flags may be specified in the
Display
subsections.
These may include driver-specific options and driver-independent options.
The former are described in the driver-specific documentation.
Some of the latter are described above in the section about the
Screen
section, and they may also be included here.

SERVERLAYOUT SECTION

The config file may have multiple
ServerLayout
sections.
A "server layout" represents the binding of one or more screens
(Screen
sections) and one or more input devices
(InputDevice
sections) to form a complete configuration.
In multi-head configurations, it also specifies the relative layout of the
heads.
A
ServerLayout
section is considered "active" if it is referenced by the
-layout
command line option or by an
Option "DefaultServerLayout"
entry in the
ServerFlags
section (the former takes precedence over the latter).
If those options are not used, the first
ServerLayout
section found in the config file is considered the active one.
If no
ServerLayout
sections are present, the single active screen and two active (core)
input devices are selected as described in the relevant sections above.

Each
ServerLayout
section must have an
Identifier
entry and at least one
Screen
entry.

The
Identifier
entry specifies the unique name for this server layout.
The
ServerLayout
section provides information specific to the whole session, including
session-specific
Options.
The
ServerFlags
options (described above) may be specified here, and ones given here
override those given in the
ServerFlags
section.

The entries that may be used in this section are described here.

Screen screen-num "screen-id" position-information

One of these entries must be given for each screen being used in
a session.
The
screen-id
field is mandatory, and specifies the
Screen
section being referenced.
The
screen-num
field is optional, and may be used to specify the screen number
in multi-head configurations.
When this field is omitted, the screens will be numbered in the order that
they are listed in.
The numbering starts from 0, and must be consecutive.
The
position-information
field describes the way multiple screens are positioned.
There are a number of different ways that this information can be provided:

x y

Absolute x y

These both specify that the upper left corner's coordinates are
(x,y).
The
Absolute
keyword is optional.
Some older versions of XFree86 (4.2 and earlier) don't recognise the
Absolute
keyword, so it's safest to just specify the coordinates without it.

RightOf "screen-id"

LeftOf "screen-id"

Above "screen-id"

Below "screen-id"

Relative "screen-id" x y

These give the screen's location relative to another screen.
The first four position the screen immediately to the right, left, above or
below the other screen.
When positioning to the right or left, the top edges are aligned.
When positioning above or below, the left edges are aligned.
The
Relative
form specifies the offset of the screen's origin (upper left corner)
relative to the origin of another screen.

InputDevice "idev-id" "option" ...

One of these entries should be given for each input device being used in
a session.
Normally at least two are required, one each for the core pointer and
keyboard devices.
If either of those is missing, suitable
InputDevice
entries are searched for using the method described above in the
INPUTDEVICE
section. The
idev-id
field is mandatory, and specifies the name of the
InputDevice
section being referenced.
Multiple
option
fields may be specified, each in double quotes.
The options permitted here are any that may also be given in the
InputDevice
sections.
Normally only session-specific input device options would be used here.
The most commonly used options are:

"CorePointer""CoreKeyboard""SendCoreEvents"

and the first two should normally be used to indicate the core pointer
and core keyboard devices respectively.

MatchSeat seat-id

Only apply this
ServerLayout
section if X server was started with
-seatseat-id
option.

Options

In addition to the following, any option permitted in the
ServerFlags
section may also be specified here.
When the same option appears in both places, the value given here overrides
the one given in the
ServerFlags
section.

Option "IsolateDevice" "bus-id"

Restrict device resets to the specified
bus-id.
See the
BusID
option (described in
DEVICE SECTION,
above) for the format of the
bus-id
parameter.
This option overrides
SingleCard,
if specified.
At present, only PCI devices can be isolated in this manner.

Option "SingleCard" "boolean"

As
IsolateDevice,
except that the bus ID of the first device in the layout is used.

Here is an example of a
ServerLayout
section for a dual headed configuration with two mice:

DRI SECTION

This optional section is used to provide some information for the
Direct Rendering Infrastructure.
Details about the format of this section can be found on-line at
<http://dri.freedesktop.org/>.

VENDOR SECTION

The optional
Vendor
section may be used to provide vendor-specific configuration information.
Multiple
Vendor
sections may be present, and they may contain an
Identifier
entry and multiple
Option
flags.
The data therein is not used in this release.